Introduction to Radiography and Computed Tomography · e ( ) x I I T = = - m 0 I 0 I Mirror at 45° Neutrons Light Light-tight Box Aperture ( ) ( ) M N A t U = m V mis the attenuation

ORNL is managed by UT-Battelle for the US Department of Energy

Introduction to Neutron Radiography and Computed Tomography

Hassina Bilheux

Neutron Imaging ScientistCellphone #: 865-384-9630

June 19th, 2019

Neutron School Team: Shawn ZhangJean BilheuxHassina Bilheux

2 Bilheux - Imaging

High Flux Isotope Reactor (HFIR) Intense steady-state neutron flux and a high-brightness cold neutron source

Spallation Neutron Source (SNS) World’s most powerful accelerator-based neutron sourceDedicated Imaging

Instrument (CG-1D)Steadily improving capabilities

Expanded support

Techniques such as Bragg-edge imaging are being

implemented on BL3 SNAP diffractometer (VENUS is

the future imaging beamline)

Imaging is a Growing Part of the ORNL Neutron Sciences Program

3 Bilheux - Imaging

Neutrons Measure Structure and Dynamics

10-11 10-9 10-7 10-5 10-3

Dimension (meters)

0.1Å 1.0nm 1mm0.1mm 10.0mm

Neutron Diffraction Neutron Scattering Neutron Microscopy Neutron Imaging

Inferred structure (indirect) Direct structure

Nuclear and electronic density in enzymes

SANS used to construct protein kinase A (PKA)

Fluid interactions in plant-groundwater systems

Soil-root interface (rhizosphere)

In Vivo Study of Embolism Formation

Computed tomography

Characterization of biological membranes, colloids, porosity, etc.

Neutron diffraction of D2 sorption in Cu3[Co(CN)6]2

Ice/water segregation in permafrost structures

500 mm

400 mm

300 mm

200 mm100 mm

50 mm

25 mm

You can directly see

the structure.

Spatial resolution is

limited!

50-100 mm routinely available25 mm available with trade-off in

field-of-view and acquisition times

4 Bilheux - Imaging

Neutrons can detect light elements such as H buried in heavy elements such as Fe

[M. Strobl et al., J. Phys. D: Appl. Phys.

42 (2009) 243001]

Neutron Radiograph X-ray Radiograph

Neutron Radiograph of

Rose in Lead Flask

Courtesy of E. Lehmann,PSIIsotope Sensitivity (important for soft matter studies)

Neutron CT of an

Inconel Turbine Blade

5 Bilheux - Imaging

HFIR CG-1D Imaging has a broad scientific portfolio

Soft Matter and Polymers, 3%

Materials for infrastructure, 3% Materials

degradation, 3%Composites, 3%

Biomass and Biofuels, 3%

Porous media, 6%

Nuclear materials, 6%

Medical applications, 6%

Industrial applications , 6%

Earth and environmental

science, 6%Life science , 9%Fluids , 9%

Phase transformations/kin

etics, 11%

Energy materials , 11%

Materials science -General, 17%

6 Bilheux - Imaging

Neutron imaging supports applied research with academia, industry and government agencies

7 Bilheux - Imaging

Game #1: Can you guess what this neutron radiograph represents?

8 Managed by UT-Battellefor the U.S. Department of Energy

What is imaging?• Imaging is the visual representation of an object: photography,

cinematography, medical imaging, X-ray imaging, thermal imaging, molecular imaging, neutron imaging, etc.

• Digital Imaging is a field of computer science covering images that can be stored on a computer as bit-mapped images


Image Modalities and Imaging Science & Technology throughout Nobel Prize history• 1901: Roentgen, FIRST Nobel Prize in Physics,

Discovery of X-rays

• 1932: Chadwick, Nobel Prize in PhysicsDiscovery of Neutrons

• 1979: Cormack and Hounsfield, Nobel Prizein Medicine, Computed Tomography (CT)

• 1986: Ruska, Binnig, Rohrer, Nobel Prize in Physics, Electron Microscopy

• 2003: Lauterbur and Mansfield, Nobel Prize in Medicine, Magnetic Resonance Imaging (MRI)

• 2009: Boyle and Smith, Nobel Prize in Physics,Imaging semi-conductor circuit, the CCD* sensor

• (*) Charge-Coupled Device


Early neutron imaging measurements

• Neutron Imaging started in the mid 1930’s but only during the past 30 years has it come to the forefront of non-destructive testing

• Dedicated world class imaging user facilities such as NIST, PSI, HZB, FRM-II, J-PARC and at many worldwide universities

• World conferences and workshops being held regularly

• Growing worldwide user community

Discovery of neutron in 1932 by Chadwick

First neutron radiograph in 1935

Left to right: Pressure gauge with metal backplate; fire hydrant and test tubes filled with H2Oand D2O imaged with gamma-rays (top) and neutrons (bottom)[ Kallman and Kuhn, Research 1, 254 (1947) ]


Multiple scattering and low detector spatial resolution

[ J. Anderson et al., Br. J. Radiol. 37, 957 (1964) ]


Today: Comparison microscopy/microCTand neutron radiography

• 92% of the pixel intensities agreement between histological and neutron

Watkin, K. et al., Neutron Imaging and Applications, Springer, 2009.

13 Bilheux - Imaging

Quantitative Neutron Imaging

Sample Scintillator

Lambert-Beer Law:

CCD Camera

( )( )

( ) xeI

IT −== m

0

I0

I Mirror

at 45°

Neutrons

Light

Light-tight Box

Aperture

( ) ( )M

NAt

m =

m is the attenuation coefficient and x is the thickness of the sample

t() is the material’s total cross section for neutrons, is its density, NA is Avogadro’s number, and M is the molar mass.

Neutron Source


Data Normalization for Imaging

• 2D – Radiography

– Normalization

=

-

-Image Dark Field

Dark FieldOpen Beam

Normalized Image1

0Transmission

( ) ( ) ( )( ) ( ) ji,DF-ji,OB

ji,DF-ji,I=ji, IN


Computed/Computerized Tomography (CT)

• Several techniques:

– Filtered Back Projection

• Radon transform

• Works well with high signal to noise ration measurements

• Easy-to-use commercial, semi-automated software available

• Quick

– Iterative Reconstruction

• Direct approach

• Less artifacts

• Can reconstruct incomplete data

• High computation time


Raw Data:

2048x2048 pixels,

~800 projections

Normalized Data:

2048x2048 pixels,

~800 projections

Sinograms:

2048x721 pixels,

2048 files

Slices:

2048x2048 pixels,

2048 slices

3D reconstruction:

2048x2048x2048

voxels

Computed/Computerized Tomography (Filtered Back Projection)

~32760~910 Counts 10 Transmission 10 Transmission ∞0 Attenuation

Turbine Blade CT Video available here

https://www.youtube.com/watch?v=eLTJlbqICno&feature=youtu.be


Detection of “imaging” neutrons

• Scintillator-based techniques such as 6Li(n,α) 3H– Good signal-to-noise (SNR) ratio– Large Field Of View (FOV) and 0.01 to hundreds of seconds

images– BUT spatial resolution limited by the dissipation of particles– Can take a lot of neutron flux!

Aperture of diameter D

Collimator

Source

Sample of thickness x

Scintillator

CCD

Lens

I0 I

LMirror

1,1 1,2 1,3 … … 1, ny

2,1 2,2 2,3 … … 2, ny

3,1 3,2 … … … 3, ny

… … … … … …, nx

nx, 1 nx, 2 nx, 3 … … nx,ny

Each pixel is coded using n-bit.16-bit = pixel value is between 0 and 65535


Detection of “imaging” neutrons (cont’d)

• Pixelated detectors – Micro-Channel Plate (MCP)– In the direct path of the beam– Limited FOV for high spatial resolution MCPs

• 1.4 cm x 1.4 cm at ~ 15 microns– Encodes events at x, y position and time of

arrival, at high temporal resolution ~ 1 MHz– Detection efficiency has improved for both

cold (~70%) and thermal (~50%) energy range

– Absence of readout noise– Not as gamma sensitive– Becoming commercial– BUT: works in relatively low-signal beam!http://www.novascientific.com/neutron.html

Courtesy of Prof. A. Tremsin, UC-Berkeley

19

CG-1D: Cold Neutron Imaging Beamline at HFIRThe CG-1D neutron imaging beamline is designed to probe structural features of length scales between ~ 25-100 µm and a few mm and kinetic changes on time scales between a few µs (repetitive motion events) to hours across a wide variety of subjects (e.g., batteries, engineering components, geological systems, biological systems, archeology and condensed matter).


CG-1D Neutron Imaging Facility (HFIR)

Lens

CC

D

Scin

tilla

tor

NeutronsLight

Detector assembly (side view)

Detector

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0 2 4 6 8 10

Neu

tro

n C

ou

nts

Wavelength (Å)

Neutron wavelength distribution at CG-1D


Conventional Neutron Imaging Techniques at Steady-State (HFIR) Sources• Radiography• Tomography • Stroboscopic Imaging• Imaging of processes that happen fast• Polarized Neutron Imaging• Monochromatic Imaging• Grating Interferometry (Phase and Dark

Field Imaging)– Under development– Increased spatial resolution and different

contrast mechanism (less than 20 mm)

Routinely available at CG-1D

Available at CG-1D using the MCP detector

Newly implemented at CG-1D


Neutron Imaging Techniques at pulsed sources (SNS)

• Wavelength-dependent (or Time-of-Flight) imaging– Contrast enhancement– Bragg edge– Resonance Imaging/Spectroscopy

• Stroboscopic imaging– SNS has a natural clock

• Neutron Imaging at energies not accessible at reactor facilities– Mainly bio-medical applications

Available at SNS SNAP using the MCP detector


2D resonance imaging measurement of tantalum foil during testing of the lead shielding. The blue data points are the calculated ideal spectrum and the red show the measured spectrum.

Photograph of the 4-in thick lead shielding and support table at the SNAP beamline

with the MCP detector.

Table supporting the Pb shielding

Modular Pb shieldingMCP detector

Resonance imaging allows isotopic mapping at the SNS

✓ Measurements performed at SNS with the micro-channel plate (MCP) detector.

✓ Technique works great up to neutron energies of ~ 300 eV (heavier elements).

✓ However, cannot separate peaks from light elements such as C, H, O, and spatial resolution is ~ 150-200 microns (faster neutrons are harder to slow down and detect).

24

Principle of wavelength-dependent neutron radiography (or Bragg edge imaging)• Spallation neutron sources discriminate neutron wavelength (or energy) by using the time-of-flight

(TOF) technique

xeII )(

0 )()( m −=M

N At

m )()( =

White-beam (or reactor-based) neutron radiograph:

sums over all neutron wavelengths

Wavelength-dependent (or TOF) neutron radiographs

(Discrete neutron wavelengths)

t1 or λ1

t2or λ2

tnor λn

2.0 cm

0.25

0.3

0.35

0.4

0.45

0.5

0.55

1.4 1.9 2.4 2.9Tran

smis

sion

Wavelength (Angstroms)

(3

(220)

(3(3

(311

(400)

(420)

25

Theory of wavelength-dependent neutron radiography• T =

𝐼(𝜆)

𝐼0(𝜆)= exp(−𝑛𝜎𝑡𝑜𝑡 𝜆 𝑧)

• 𝜎𝑡𝑜𝑡 = 𝜎𝑎𝑏𝑠 + 𝜎𝑖𝑛𝑐𝑜ℎ 𝑒𝑙𝑎 + 𝜎𝑖𝑛𝑐𝑜ℎ 𝑖𝑛𝑒𝑙𝑎 + 𝜎𝑐𝑜ℎ 𝑖𝑛𝑒𝑙𝑎 + 𝜎𝐵𝑟𝑎𝑔𝑔

• 𝜎𝐵𝑟𝑎𝑔𝑔(𝜆) =𝜆2

4𝑉0

ℎ𝑘𝑙

2𝑑ℎ𝑘𝑙<𝜆 𝐹ℎ𝑘𝑙2𝑑ℎ𝑘𝑙 𝑃 𝛽ℎ𝑘𝑙 𝐸ℎ𝑘𝑙 𝜆, 𝐹ℎ𝑘𝑙

• 𝛽ℎ𝑘𝑙 = arcsin(λℎ𝑘𝑙

2𝑑ℎ𝑘𝑙)

• 𝑃 𝛽ℎ𝑘𝑙 =1

𝜋−𝜋

2

𝜋

2 ቂ

ቃ

𝑟ℎ𝑘𝑙2 −

1

𝑟ℎ𝑘𝑙(

)

cos 𝛼ℎ𝑘𝑙 𝜆 cos 𝛽ℎ𝑘𝑙 −

sin 𝛼ℎ𝑘𝑙 𝜆 sin 𝛽ℎ𝑘𝑙 sin𝜑2 +

1

𝑟ℎ𝑘𝑙

−3

2𝑑𝜑, where 𝛼ℎ𝑘𝑙 =

𝜋

2−

arcsin(λℎ𝑘𝑙

2𝑑ℎ𝑘𝑙)

E. Fermi, W. Sturm, R. Sachs. The transmission of slow neutrons through microcrystalline materials, Physical Review 71 (1947) 589.

Degree of crystalline anisotropy

Most probable angle of preferred grain orientation

Depends on the crystallite size along the beam direction

26

• 𝐸ℎ𝑘𝑙 𝜆, 𝐹ℎ𝑘𝑙 = 𝐸𝐵𝑠𝑖𝑛2𝜃ℎ𝑘𝑙 + 𝐸𝐿𝑐𝑜𝑠

2𝜃ℎ𝑘𝑙

• 𝐸𝐵 =1

1+𝑥

• 𝐸𝐿 = 1 −𝑥

2+

𝑥2

4−

5𝑥3

48+

7𝑥4

192for x ≤ 1

• 𝐸𝐿 =2

𝜋𝑥1 −

1

8𝑥−

3

128𝑥2−

15

1024𝑥3for x > 1

• 𝑥 = 𝑆2(𝜆𝐹ℎ𝑘𝑙

𝑉0)2, where S is proportional to the crystallite size along the beam direction

Theory of wavelength-dependent neutron radiography (cont’d)

T.M. Sabine, R.B. Von Dreele, J.-E. Jorgensen. Extinction in time-of-flight neutron powder diffractometry, Acta

Crystallographica Section A 44 (1988) 374-379.

T. Sabine. A reconciliation of extinction theories, Acta Crystallographica Section A: Foundations of Crystallography 44 (1988)

368-374.

Back-scatter and Laue (forward-scatter) contributions

27

1.5 2.0 2.5 3.0 3.5 4.0 4.50

20

40

60

80

100

Barn

s

Wavelength (Å)

Total Cross Section Coherent Elastic Incoherent Elastic Coherent Inelastic Incoherent Inelastic Absoption

311 220222 200 111

1.5 2.0 2.5 3.0 3.5 4.0 4.5

40

60

80

100

to

t (Ba

rns)

Wavelength (Å)

1 mm

5 mm

10 mm

311 220222 200 111

1.5 2.0 2.5 3.0 3.5 4.0 4.50

100

200

300

() r= =

() r= =

() r= =

to

t (Ba

rns)

Wavelength (Å)

No texturer = 1 for all (hkl)

311 220222 200 111

() r= =

𝜎𝐵𝑟𝑎𝑔𝑔 𝜆 =𝜆2

2𝑉0

ℎ𝑘𝑙

2𝑑ℎ𝑘𝑙>𝜆

𝐹ℎ𝑘𝑙2𝑑ℎ𝑘𝑙 𝑃 ൯𝛼ℎ(𝜆 𝐸ℎ𝑘𝑙 𝜆, 𝐹ℎ𝑘𝑙

Total cross section for Inconel 718

Crystallite size effect(Ehkl)

Crystallite orientation effect (𝑷 ൯𝜶𝒉(𝝀 : r and β)

March-Dollasemodel

Sabine’s primary

extinction model

Song, et al., “Thermally-Induced Dynamic Evolution of Additively Manufactured Metal Microstructures”, J. of Imaging, 2017.

1. Granada, J. R. Zeitschrift für Naturforschung A 39, 1160 (1984).2. 2. Binder, K. physica status solidi (b) 41, 767-779 (1970).

1. Vogel, S. PhD thesis, Christian-Albrechts Universität Kiel, (2000).

2. Sabine, T. Acta Crystallographica Section A. 44, 368-374 (1988).

𝜆: wavelength𝑉0: volume of unit cell

Fhkl: Structure factor including Debye-Waller factor

dhkl: plane spacing

rhkl: crystallite anisotropyβhkl: most probable angle

Theory of wavelength-dependent neutron radiography (cont’d)

Validation of Bragg-edge imaging results using neutron diffraction

2.0 2.5 3.0 3.5 4.0 4.50

60

80

100

120

140

160

to

t (B

arns

)

Wavelength (Å)

Calculated Experiment Difference

311 220 200 111

𝜎𝐵𝑟𝑎𝑔𝑔 𝜆 =𝜆2

2𝑉0

ℎ𝑘𝑙

2𝑑ℎ𝑘𝑙>𝜆

𝐹ℎ𝑘𝑙2𝑑ℎ𝑘𝑙 𝑅(𝜆, 𝑑_ℎ𝑘𝑙)

20 30 40 50 60 70 80 900

1

2

3

4

5

6

7 Orientation: 0

R(

d

hkl):

Pro

babi

lity

Bragg angle (°)

111 200 220 311

Bunge, H.-J. Texture analysis in materials science: mathematical methods. (Elsevier,

2013)

Texture measurements at SNS VULCANBragg edge CT at SNS SNAP

29

SNS SNAP Imaging (“Temporary” Capability soon available in user program)

0

20

40

60

80

100

120

140

160

180

200

1.25 2.25 3.25 4.25

Tran

smis

sion

(a.u

.)

Wavelength (Angstroms)

SNAP, RUN #0 vs. Run #8

SNAP , RUN #8 T0 phased, meteorite + DOE sample,BDW = 1 to 4.1 Angs, centered at 2.55 Angs

SNAP, Run #0, T0 dephased, OB + 1.5 inch Al block,BDW=1.7 to 4.85 Angs, centered @3.275 Angs

Game #2: What is this peak due to?

30

Neutron radiography and data reduction at a pulsed source

Slit system

Sample

MCP

detectorIncident pulsed

neutron beam

Two-dimensional TOF

neutron radiograph

Empty place

(Open

Beam: OB)

Region of

interest

2.0 2.5 3.0 3.5 4.0 4.5

to

t (a.u

.)

Wavelength (Angs.)

Bragg-edges

Incident neutron (I0)

Transmitted neutron (I1)

Transmitted neutron (I2)

Sample

In-situ

measurements

(load frame or

furnace)

Pixel size:

55*55 μm2

Field of view: 2.8 *2.8 cm2

Extract crystallographic information

from the Bragg-edge spectrum

Best option for data reduction but sometimes sample

occupies whole detector area

Second best option is to use a beam monitor

SNS energy distribution varies as a function of beam

power

Cannot measure as a function of time but need to measure as a function of protons on

target

Gamma discrimination is extremely important for

resonance imaging


Engineering Materials

32

NOT NECCESSARILLY TO SCALE; FOR ILLUSTRATIVE PURPOSES ONLY.

A

A

A

B B

B

C

C

C

Many samples prepared using two Inconel 718 blocks with different crystallite structures

Tensile samples(~ 30 x 5 x 5 mm3)

Compression samples

(~ 12 x 5 x 5 mm3)

Stan

dard

Mel

t Modified M

elt

33

In-situ heating of AM Columnar Inconel 718 coupon

Comparison

• Before heating: two dominant microstructure orientations (200) and (311)

• As temperature increases, Bragg edge shifts toward higher , as expected during thermal expansion

• Bragg edges decrease with increased temperature due to Debye Waller effect (grain vibrations)

• During cooling, decrease of (200) and presence of (111) grains

• Final microstructure close to powder sample data (i.e. random grain orientation)

• Data arbitrarily shifted along y-axis to show the different plots

34

Fitting and interpretation of the data

• rhkl = 1, random grain orientation

• rhkl =/ 1, fiber or plate-shaped distribution (i.e. here columnar)

• S (in microns) increases as a function of temperature, from 1 to 2.6, and finally reaching 10.7, indicating grain size growth

(200) (111)

35

Bragg edge fitting with JupyterNotebooks

36

Software: a required tool for accurate and fast processing of wavelength-dependent neutron radiography: iBeatles

37

38

neutronimaging.pages.ornl.gov

Step-by-step tutorials with animated

demonstrations

Something you want to see on our user

website? Contact Jean Bilheux

[email protected]

mailto:[email protected]

39

Image Processing and Analysis

• Data normalization and 3D reconstruction are considered part of the pre-processing steps

• Image Processing and Analysis are often complex when trying to quantify data and require three main ingredients:– advanced skills– “good” size computer/server– advanced visualization techniques/software to interact with your data

• We don’t expect you to know how to do this, but we expect you to help us develop the algorithms to extract the information you need– Not just “pretty pictures” but a 3D quantitative technique


Fabrication tolerance studies comparing CAD drawing to neutron computed tomography

+

Engineering drawing Neutron CT

=

In orange/yellow: AUTOCAD outlineIn gray: neutron data



Micro X-ray CT of AM samples

5 mm x 5 mm base Inconel 718


The Nature of Electrochemical Delithiation of Li-Mg Alloy Electrodes: Neutron Computed Tomography and Analytical Modeling

This research was supported by DoE-BES grant DE-FG0212ER46891. Measurement was performed at theORNL High Flux Isotope Reactor CG-1D imaging beamline. This effort was supported by Scientific UserFacilities Division, Office of Basic Energy Sciences, US Department of Energy.

Top: Cross-sectional views of 3D reconstructedpseudo-color images of Mg-70 wt.% (~89 at.%) Lialloy depleted to various depths.Bottom: Simulated vs. experimental data for Mg-70wt.% Li with depletion of (a) 0%, (b) 17.78%, (c)32.34% and (d) 41%.

Y. Zhang, K.S.R. Chandran, M. Jagannathan, H.Z. Bilheux, J.C. Bilheux, Journal of The Electrochemical Society, 164 (2017) A28-A38.

Scientific AchievementLi concentration profiles in electrochemically delithiated Li-Mg alloy electrodes have been quantitatively determined using neutron computed tomography (CT). A rigorous analytical model to quantify the diffusion-controlled delithiation, accompanied by phase transition and phase boundary movement, has also been developed.

Significance and Impacto The variations in Li conc. caused by different depths of delithiation can

be clearly observed in the neutron tomographic data. o The simulated Li concentration profiles agreed well with the tomographic

data. The modeling approach is exact and is applicable for modeling delithiation of any Li-containing electrode.

o Neutron CT can be used to validate kinetic model for Li-containing electrode.

Research Detailso Alloy electrodes with two compositions, Mg-70 wt.% Li and Mg-50 wt.%

Li, were delithiated to various depths of Li depletion in Swagelok cells. o Neutron CT scan was performed at CG-1D beamline using a charge-

coupled device (CCD).o Analytical solutions for Li conc. profile were obtained by solving Fick’s

second law using variable separation method with initial and boundary conditions.

o Li diffusivity used for modeling was validated by chronoamperometric test and Cottrell equation.

44

Neutron Radiography and CT of batteries

➢Can spatially map inhomogeneities and degradation of the cell in 2D (in-operando) and 3D (ex-situ)➢Quantitative measure of Li concentration: correlates contrast with local Li concentration

2D 3D

45 D01 D12

How to enhance contrast in batteries other than Li batteries?

Isotope Coh xs Inc xs Scatt xs Abs xs

Zn 4.054 0.077 4.131 1.11

64Zn 3.42 0 3.42 0.93

66Zn 4.48 0 4.48 0.62

67Zn 7.18 0.28 7.46 6.8

68Zn 4.57 0 4.57 1.1

70Zn 4.5 0 4.5(1.5) 0.092

C. Grünzweig, F. Pfeiffer, O. Bunk, T. Donath, G. Kühne, G. Frei, M. Dierolf, C. David, Design, fabrication, and

characterization of diffraction gratings for neutron phase contrast imaging. Review of Scientific Instruments 79, -

(2008).

✓ Technique resolution and contrast, based on fitting amplitude and

shift of signal is decoupled from the instrument resolution.

✓ Capability to detect features down to 500 nm.

n(x,y,z) = 1 - (x,y,z) + i(x,y,z)

phase attenuation

d = l 2Nbc

2pb = s t (l)

rNA

M

l

2p

46

Neutron Grating Interferometry (nGI) at CG-1D

E. Lehmann, K. Lorenz, , E. Steicheleb, P. Vontobel, Non-destructive testing with neutron phase contrast, Nuclear Instruments and Methods A 542, 2005.

Neutron phase shift values projected on each pixel.

Attenuation-based radiograph of Cu and Ti samples.


Scientific AchievementSpontaneous imbibition of liquids into gas-filled fractures in variably-saturated porous media is important in a variety of engineering and geological contexts. Dynamic neutron radiography was applied to directly quantify this phenomenon in terms of sorptivity and dispersion coefficients.

Rapid Imbibition of Water in Fractures within Unsaturated Sedimentary Rock

Work performed at the High Flux IsotopeReactor Imaging beam line (CG1D) wassupported by the Scientific User FacilitiesDivision, Office of Basic Energy Sciences,U.S. Department of Energy.

Significance and ImpactThe theory derived describes rapid early-time water movement into air-filled fractures in sedimentary rock. Both theory and observations indicate that fractures significantly increase spontaneous imbibition and dispersion of the wetting front in unsaturated sedimentary rocks. Capillary action appears to be supplemented by surface spreading on rough fracture faces. The findings can be applied in modeling hydraulic fracturing.

Research DetailsImbibition into unsaturated Berea sandstone cores was controlled with a Mariotte bottle setup. Images were collected using dynamic neutron radiography and analyzed using ImageJ.

Cheng C. -L., Perfect E., Donnelly B., Bilheux H. Z., Tremsin A. S., McKay L. D., DiStefano V. H., Cai J. C., Santodonato L. J., Rapid imbibition of water in fractures within unsaturated sedimentary rock. 2015. Advances in Water Resources, Volume 77, Pages 82–89 <http://dx.doi.org/10.1016/j.advwatres.2015.01.010>

Time sequence of neutron radiographs showing the rapid uptake of water into a longitudinal, air-filled fracture zone in Berea sandstone (~50 mD). FOV is ~28 x 28 mm2.

48 Industry Advisory Board Meeting, April 12-13, 2017

Scientific AchievementEmployed neutron tomography to measure the properties of soot cake layer thickness and subsequently density during a sequential regeneration. Identified key parameters that will aid understanding of the fuel-consuming regeneration process.

Neutron Computed Tomography Characterizes Particulate Properties During Regeneration

Work performed at the High Flux IsotopeReactor Imaging (CG1D) beamline wassupported by Scientific User FacilitiesDivision, Office of Basic Energy Sciences,US Department of Energy.

Significance and ImpactUnderstanding the regeneration progression of DPFs is important in improving the efficiency of the process and to understand the correlation between pressure drop and soot level. The results from this work can directly provide model parameters to industry so they can better predict the level soot/particulate in the DPFs.

Research Details• DPFs were filled to different levels (3, 5 and 7 g/L) using diesel

engine• Full DPFs analyzed with neutron tomography to determine the

soot cake thickness and packing density• Soot cake density, thickness and axial profile measured during

sequential regeneration• Highest soot cake density observed during initial 20%

regeneration; layer then loses density, porosity increases and channels open up

• Different soot loading displayed same behavior during regeneration

T. J. Toops, H. Bilheux, S. Voisin, J. Gregor, L. Walker, A. Strzelec, C. E. A. Finney, J. A. Pihl, Nuclear Instruments and Methods in Physics Research Section A 729 (2013) 581-588.T. J. Toops, J. A. Pihl, C. E. A. Finney, J. Gregor, H. Bilheux, Emission Control Science and Technology 1:1 (2015) 24-31.

DPFs collect soot during engine operation, leading to soot cake. During regeneration soot cake properties change significantly as identified in neutron imaging campaign.

Diesel particulate filters (DPF) clean exhaustand reduce pollution

Soot-filled DPF

0.5 in (1.3 cm)

Clean DPF


Biological and Environmental Applications


Neutron Radiography of Roots at CG1-D

•Water injected into root zone at base

•Unidentified endophyte (symbiotic) or decomposer fungi visible near roots

of switchgrass (left), revealing substantial hydration of the rhizosphere

•Both fine and coarse roots are readily visible

Switchgrass and MaizePlants in Al chamber

J. Warren (PI), H, Bilheux, M. Kang, S. Voisin, C. Cheng, J. Horita, E. Perfect, Plant Soil, 2013


Investigating novel contrast agents for biological applications

• Observation of water fluxes in soil/root surrounded with fungi is challenging due to lack of contrast between fungi and water• Unlike heavy water (D2O) which provides a lesser image contrast, the use of Gd compounds

as tracers provide a strong neutron attenuation (i.e. contrast) that can be followed as a function of time in a plant system.

• Gd-compounds are good candidates to serve as tracers for solid movements – possible use as a tracer for nutrients (e.g. phosphorus, nitrogen).

• Gd-based MRI contrast agents prepared as a liquid solution (0.25-1M concentration) were hydroponically fed to plants prior to conducting the imaging experiments.

• Toxicity of Gd compounds will need to be evaluated through time.

Courtesy of DeCarlo K., Jacobson S., Bilheux, (2017).


Changes in Soil and Root Water Content using Neutron Radiography

Distance across root (mm)0 2 4 6 8

Wat

er c

onte

nt (r

elat

ive)

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.253 hours7 hours12 hours

Top – More water showing up based on division (white areas)

Blue arrows show where water was removed from the system.

Left – increase in water content or root or rhizosphere due to root growth or root water efflux

t = 0 h t= 12 h t= 12/t= 0

J. Warren (PI), H, Bilheux, M. Kang, S. Voisin, C. Cheng, J. Horita, E. Perfect, Plant Soil, 2013


Neutron sensitivity to H atoms and thus observe Water Uptake by Roots and Stem

10-d old maize seedling (A) aluminum sample chamber; (B) neutron radiograph at ~70 µm pixel resolution illustrating roots distribution (0.2-1.6 mm); C) 3D tomographic reconstruction; (D) Timing of water uptake by plant components highlighted in (B) illustrating impact of solar radiation on rate of water flux in stem and ~0.5 mm first and second order roots.

➢ This study provides direct evidence for root-mediated hydraulic redistribution of soil water to rehydrate drier roots

Plant Soil, 2013, DOI 10.1007/s11104-012-1579-7

Time since water pulse (h)0 1 2 3 4 5 6 7 8

Wat

er c

onte

nt (r

elat

ive

chan

ge)

0.00

0.05

0.10

0.15

0.20

Stem Root 1Root 2Root 3

OFF ON ONOFF OFF

LAMPON

R1

R2 R3

A B C D

MRI, X-CT, and NR imaging techniques

Maria Cekanova

NR

CortexMedullaCapsule

Fat in the renal sinus

Renal Pelvis

A

MRI

C D

X-CT

B

NRCourtesy of Dr. Maria Cekanova, The University of

Tennessee, College of Veterinary Medicine


Scientific Achievement PMI was objectively estimated by measuring changes in neutron transmission correlated with H content variation in decaying tissues.

Significance and Impact– One of the most difficult challenges in forensic research

for criminal justice investigations is to objectively determine post-mortem interval (PMI).

– The estimation of PMI is often a critical piece of information for forensic sciences.

– Most PMI techniques rely on gross observational changes of cadavers that are subjective to the forensic anthropologist.

Research Details– Tissues exposed to controlled (laboratory settings) and

uncontrolled (University of Tennessee Anthropology Research Facility) environmental conditions.

– Neutron radiographs were compared to histology data to assess the decomposition stage

– Over a period of 10 days, changes in neutron transmission through lung and muscle were found to be higher than bone by 8.3%, 7.0%, and 2.0%, respectively.

A novel approach to determine post-mortem interval using neutron radiography

H. Z. Bilheux , M. Cekanova, A. A. Vass, T. L. Nichols, J. C. Bilheux, V. Finochiarro,

Forensic Science International, doi:10.1016/j.forsciint.2015.02.017 (March 2015)

(A) Photograph, (B) gray scale and color enhanced (C) neutron radiograph of a 2 cm × 2 cm × 1 mm thick skeletal muscle tissue. (D) Neutron transmission as a function of time of skeletal muscle tissues under controlled conditions with natural logarithm fit.

Work performed at ORNL’s High Flux IsotopeReactor CG-1D and Spallation Neutron SourceVULCAN beamlines was supported by ScientificUser Facilities Division, Office of Basic EnergySciences, US Department of Energy. Part of thisresearch sponsored by NIJ.


Day 2Day 0 Day 3 Day 4

Day 1 Day 2Day 0

Day 4Day 3

A novel approach to determine post-mortem interval using neutron radiography (cont’d)

Game #4: How long does it take for an average size adult cadaver to turn to bones in a hot and humid summer in

TN?

57

Acknowledgments

• Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle LLC, for DOE.

• Resources at the High Flux Isotope Reactor (HFIR) and Spallation Neutron Source (SNS), U.S. DOE Office of Science User Facilities operated by ORNL, were used in this research.

• Research at Manufacturing Demonstration Facility (MDF) was sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

• Thanks to J. Molaison, M. Frost and H. Skorpenske for setting up the detector and furnace at the SNS beamlines.


Thank you

([email protected])

Courtesy ofProf. Krysta Ryzewski, Wayne UniversitySusan Herringer, Prof. Brian Sheldon, Brown University

Documents

Introduction to Radiography and Computed Tomography · e ( ) x I I T = = - m 0 I 0 I Mirror at 45° Neutrons Light Light-tight Box Aperture ( ) ( ) M N A t U = m V mis the attenuation